New to CAM/CNC, how to troubleshoot general toolpath issues?

[Anonymous]

Hey there. I'm new enough to this side that I might not be using the right terms, so please bear with me. I'm working on a project to mill a tile design (into wood). I'm coming from some experience with FDM, and learning that I may need to alter things when thinking about subtracting material using bits. I've been able to create a CAM setup and playing around with a first pass which looks like this:

I see that it's skipping a lot, so I added a second pass with a smaller tool. It's better, but as you see below where I've circled in red, there's a lot which is not being cut. So that's my question -- how do I go about the process of resolving this so that it will cut all of the material I need it to? I've played with a bunch of settings and just seem to be going in circles at this point so could use some general troubleshooting guidance. Thanks!

[DanielMolloy · Accepted solution]

Hi @Anonymous,

Firstly, welcome to the fun! Great to see new people getting involved with machining 🙂

So there was a couple of things that were causing issues that I could see, first is that you were using a 3d adaptive roughing operation, this is designed to rough out pockets with 3d geometry so for example if the walls of the pocket weren't vertical. However in your case these pockets are just 2d pockets with vertical walls so I would recommend using the 2d adaptive operation (I have included a screenshot showing where this op can be found.

Second thing is that you combination of tool size and amount of stock to leave was causing material to be left, so the system worked out with you choosing to leave 0.5mm on the walls that the tool simply could fit (and be able to maintain its minimum cutter radius). I have attached a sample job with a toolpath that produces the cut you want so this uses a 2d adaptive cut with axial stock reduced to 0.1mm. 

Take a look at what I have attached and if you have questions just reply and I would be happy to help 🙂

[michael.grenier4GVTU]

One detail I would add, Adaptive is an amazing strategy to use for usually deep cuts in hard material.  As it better controls the amount of material the tool removes all the time, it allows you to go really deep in a single cut.  Looking at the depth of your pockets and that you are cutting wood, I think you should simply use a 2D pocket strategy in a single cut.  Yes the tool is going to be doing slot cutting many time, but it's wood, it can take it at 0.5mm deep.

Just my suggestion here having cut a lot of wood on my router that way.

[Anonymous]

Ok that was super helpful @michael.grenier4GVTU , thanks! I have two follow up questions 🙂 

3D adaptive has some techniques to control the boundaries of what will be cut (like silhouette). I don't see the same with 2D, but I'm sure there must be a way to do this. As in the example screenshot below which is a small test in a large stock, how do I prevent it from carving the other 99.9% away just to get a small test? 

And lastly, is there a quicker way to selecting 2D pockets than one-by-one? It was nice to just select the whole body in 3D and be done with it. As you saw in the design, I have dozens of these pockets.

thanks much!

[michael.grenier4GVTU]

To carve only one section, you could go back to design and create a sketch with the section you want to limit your toolpath in.  Since you are doing pocket, you need something to contain the toolpath in and you don't have this geometry on your model which means you'll have to draw it.  About selection, you can pick faces or edges, sometime a single face will include multiple boundaries so that could help depending on your part.